What would be causing my nectarines to remain hard and not grow more than a ping pong ball. The tree is about 8 years old and aside from its first year it had not set any fruit. I was very excited this year to have about 30 nectarines, but they don't appear to be growing further. They are smooth skinned, green and hard. Any ideas from the experts?
This is the tree before the leaves fully filled in and blossoms set.